91Ó°ÊÓ

mass of man: ${\mathrm{m}}_{\mathrm{body}}=70 \mathrm{kg}$

temperature of man: ${T_1}_{body}={37}^{0}C$

volume of can: $\mathrm{V}=0.355 \mathrm{L}$

mass of water in can: ${\mathrm{m}}_{\mathrm{w}}=0.355\mathrm{kg}$

temperature of water: ${T_1}_w=12{ }^{0}C$

specific heat of man’s body: $C_{\mathrm{body}}=3480 \mathrm{J}/{\mathrm{kg}}^0\mathrm{C}$

If no external heat energy is involved, then, at equilibrium, the sum total of all the changes in heat energy is equal to zero.

Given that ${\mathrm{m}}_{\mathrm{body}}=70 \mathrm{kg}$ and $T_{1_{body}}=37{ }^{0}C$. Volume of water is $\mathrm{V}=0.355 \mathrm{L}$ and its density is$1\frac{ kg}{l}$. So, this means that ${\mathrm{m}}_{\mathrm{w}}=0.355 \mathrm{kg}$. Also given that $T_{1w}={12}^{0}C$ and $C_{body}=3480 \frac{J}{k{g}^{0}C}$.

According to the heat energy equation at equilibrium

$$\begin{gathered} {\mathrm{m}}_{\mathrm{b}}×{\mathrm{C}}_{\mathrm{b}}×{\mathrm{δ°Õ}}_{\mathrm{b}}=-{\mathrm{m}}_{\mathrm{w}}×{\mathrm{C}}_{\mathrm{w}}×{\mathrm{δ°Õ}}_{\mathrm{w}} \\ {\mathrm{m}}_{\mathrm{b}}{\mathrm{C}}_{\mathrm{b}}(\mathrm{T}-{\mathrm{T}}_{\mathrm{b}})=-{\mathrm{m}}_{\mathrm{w}}{\mathrm{C}}_{\mathrm{w}}(\mathrm{T}-{\mathrm{T}}_{\mathrm{w}}) \\ \mathrm{T}=\frac{({\mathrm{m}}_{\mathrm{b}}{\mathrm{C}}_{\mathrm{b}}{\mathrm{T}}_{\mathrm{b}}+{\mathrm{m}}_{\mathrm{w}}{\mathrm{C}}_{\mathrm{w}}{\mathrm{T}}_{\mathrm{w}})}{({\mathrm{m}}_{\mathrm{b}}{\mathrm{C}}_{\mathrm{b}}+{\mathrm{m}}_{\mathrm{w}}{\mathrm{C}}_{\mathrm{w}})} \end{gathered}$$

Substituting values, we get

$$\begin{gathered} T=\frac{\left(70kg×3480J/kg°C×37°C\right)+\left(0.355kg×4190J/kg°C×12°C\right)}{\left(70kg×3480J/kg°C×37°C\right)\left(0.355kg×4190J/kg°C×12°C\right)} \\ =36.85°C \end{gathered}$$

The decrease in temperature is

$$\begin{gathered} ∆T=37°C-36.85°C \\ =0.15°C \end{gathered}$$

The thermometers are designed according to the sensitivity to the temperature change. Such a small change in the temperature can be measured by a thermometer if it is very sensitive to the temperature changes.